Method for reinforcing face-facing mining roadway narrow coal pillar by adopting opposite-pull grouting anchor cable beams
By using the tension grouting anchor beam method, utilizing the hollow-solid-hollow cable structure and expandable locking hoop design, and carrying out advance and delayed grouting in stages, the reinforcement problem of narrow coal pillars under mining stress was solved, achieving efficient coal pillar stabilization effect.
Patent Information
- Application Number
- CN202510907661.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-02
- Publication Date
- 2025-09-16
AI Technical Summary
In coal mines, when newly excavated tunnels and adjacent mining faces advance toward each other, narrow coal pillars are affected by the stresses of advanced and lagging mining, resulting in the development of cracks in the coal pillars and loose and broken surrounding rocks. The existing anchor rods and anchor cables are not effective, and the multiple grouting reinforcement process is complicated, making it difficult to achieve ideal reinforcement effects.
The method of tension grouting anchor beam is adopted. By installing through-anchor cables in narrow coal pillars and combining them with channel steel beam anchoring, advance and delayed grouting are carried out in stages to reinforce the coal pillars. The hollow-solid-hollow cable body structure and expandable locking hoop design are used to carry out two independent grouting operations to improve stability.
It achieves efficient and simple overall reinforcement of narrow coal pillars, reduces the risk of roadway deformation and coal pillar instability, and improves the stability and support effect of the coal pillars.
Smart Images
Figure CN120649958A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of mining engineering technology, and in particular to a method for reinforcing narrow coal pillars in a roadway facing mining by using tension grouting anchor beams. That is, during the process of the new roadway and the adjacent coal mining working face advancing toward each other, when the new roadway is protected by a narrow coal pillar, the narrow coal pillar is reinforced by secondary grouting through the tension grouting anchor beams. Background Art
[0002] During coal mining operations, newly excavated roadways and adjacent mining faces sometimes advance toward each other. To improve recovery rates, newly excavated roadways often employ narrow coal pillars for protection. As roadway excavation and the mining face advance, the roadway's head and the mining face gradually approach, pass each other, and gradually move away from each other. During this process, intense leading and lagging mining stresses cause cracks to develop in the coal pillars, loosening and fragmenting the surrounding rock, and resulting in significant deformation and failure. Under these conditions, coal mines often employ support methods such as bolts and cables. As cracks within the coal pillars gradually expand, the effectiveness of existing bolts and cables rapidly decreases, or even becomes unanchored and ineffective. Grouting is sometimes also employed as a reinforcement method. However, a single grouting injection rarely achieves the desired reinforcement effect, whether in leading or lagging working faces. Repeated grouting would complicate the reinforcement process. Therefore, simple and efficient reinforcement of narrow coal pillars in roadway construction with narrow coal pillars is of great practical significance. Summary of the Invention
[0003] To address the current problem of using multiple means, such as anchor bolts, anchor cables, and grouting, to comprehensively support narrow coal pillars facing mining lanes in coal mines, but with difficulty achieving synergy between these various support methods, the overly complex construction process, and poor support effectiveness, the present invention proposes a method for secondary grouting reinforcement using a pair of grouting anchor beams. The pair of grouting anchor beams is an active reinforcement technology used to improve the overall stability of coal pillars. Its core is to penetrate the coal pillar with grouting anchor cables and then anchor them at both ends with channel steel beams. Combined with secondary grouting of the leading and lagging working faces, a highly stable overall load-bearing structure is formed.
[0004] To achieve the above-mentioned purpose, the present invention provides a method for reinforcing a narrow coal pillar in a mining tunnel by using a pair of tensioned grouting anchor beams. The pair of tensioned grouting anchor beams for reinforcing a narrow coal pillar in a mining tunnel consists of a grouting anchor cable and a channel steel beam for anchoring at both ends of the grouting anchor cable. The grouting anchor cable includes a solid cable body and two hollow cable bodies connected to both ends of the solid cable body. A first hard push tube is sleeved on the solid cable body, and a second hard push tube is sleeved on the hollow cable body. An extrudable and expandable locking hoop is provided between the first hard push tube and the second hard push tube. A grouting outlet is provided on the hollow cable body, and a strip-shaped opening groove is provided on the tube wall of the hard push tube. The grouting outlet is located in the strip-shaped opening groove.
[0005] In the mining roadway, the new roadway and the adjacent coal mining face are advanced towards each other. A narrow coal pillar is used to protect the roadway between the new roadway and the roadway on the side of the coal mining face. As the coal mining face gradually advances, the reinforcement of the narrow coal pillar of the mining roadway with tension grouting anchor beams is divided into three stages:
[0006] In the first stage, the construction of tension grouting anchor beams:
[0007] For the portion of the narrow coal pillar outside the range of influence of the advanced mining of the coal mining face, an anchor cable drill hole is opened on the narrow coal pillar in this portion, which runs from the newly excavated roadway to the roadway on the side of the coal mining face, and the grouting anchor cable is installed in the anchor cable drill hole. The two ends of the grouting anchor cable are anchored by a channel steel beam. When installing the grouting anchor cable, the first hard push tube and the solid cable body are located in the middle of the anchor cable drill hole. The second hard push tube applies a thrust toward the first hard push tube to expand the locking hoop and seal the anchor cable drill hole.
[0008] The second stage is advance grouting reinforcement:
[0009] Monitor the crack development range of the narrow coal pillar within the advance mining influence range of the coal mining face, and determine the timing of advance grouting based on the crack development range of the narrow coal pillar reflected by the test results. Then, advance grouting is carried out on the narrow coal pillar through grouting anchor cables in the roadway on one side of the coal mining face.
[0010] The third stage, delayed grouting reinforcement:
[0011] For the narrow coal pillar within the range of delayed mining influence of the coal mining face, the crack development range of this narrow coal pillar is monitored, and the timing of advance grouting is determined based on the crack development range of the narrow coal pillar reflected by the test results. The narrow coal pillar is then delayed grouted by grouting anchors in the newly excavated tunnel.
[0012] As a further preferred technical solution of the present invention, the grouting anchor cable also includes a grouting plug and an anchor mounted on the hollow cable body. The grouting plug is located at one end of the hollow cable body away from the solid cable body, and the anchor is located on the outside of the grouting plug for fixing to the channel steel beam.
[0013] As a further preferred technical solution of the present invention, a plurality of grouting outlets are provided along the axial direction of the hollow cable body and at intervals.
[0014] As a further preferred technical solution of the present invention, the locking hoop is made of rubber.
[0015] As a further preferred technical solution of the present invention, the solid cable body is 1 / 3 of the length of the anchor cable drilling hole, and the lengths of the two hollow cable bodies located in the anchor cable drilling hole each account for 1 / 3 of the length of the anchor cable drilling hole.
[0016] As a further preferred technical solution of the present invention, the scope of fracture development in the narrow coal pillar is monitored by means of borehole imaging or geological radar.
[0017] As a further preferred technical solution of the present invention, in the second and third stages, when the crack development range in the narrow coal pillar exceeds the anchoring range of the anchor rod in the original support of the narrow coal pillar or 1 / 3 of the width of the narrow coal pillar, the corresponding advance grouting and delayed grouting are started.
[0018] As a further preferred technical solution of the present invention, the grouting pressure of the delayed grouting should be greater than the grouting pressure of the advanced grouting.
[0019] As a further preferred technical solution of the present invention, the tension grouting anchor beam is composed of two spaced-apart grouting anchors and channel steel beams for anchoring at both ends of the grouting anchors, and the same side of the two spaced-apart grouting anchors is anchored on the same channel steel beam.
[0020] The present invention uses a grouting anchor cable beam to reinforce a narrow coal pillar in a mining roadway. Grouting anchor cables are used to inject grout into the narrow coal pillar, sequentially on the roadway side of the mining face and then on the side of the newly excavated roadway, as the relative position of the section to be reinforced and the mining face changes. The grouting anchor cables' "hollow-solid-hollow" structure and two expandable locking hoops allow for independent grouting. This means that after the pre-grouting operation, the slurry's penetration and solidification will not affect the subsequent secondary grouting.
[0021] The method of the present invention is suitable for the case where a narrow coal pillar is left to face the mining roadway. The method uses the tension anchor beam to perform advance grouting and delayed grouting reinforcement, realizes integrated anchoring and grouting reinforcement of the narrow coal pillar, and fills the cracks by grouting reinforcement, strengthens the narrow coal pillar, and improves the stability of the coal pillar and the newly excavated roadway when the coal mining working face advances, thereby reducing roadway deformation and reducing the risk of coal pillar instability or coal pillar collapse. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0023] Figure 1 This is a schematic diagram of different construction stages and positions of the narrow coal pillar in the mining roadway in the embodiment. In the figure, the black part is the coal body and the upper left corner area is the goaf.
[0024] Figure 2 It is a schematic diagram of using tension grouting anchor beams to reinforce narrow coal pillars in mining lanes and secondary grouting reinforcement in the embodiment.
[0025] Figure 3 It is a structural schematic diagram of the grouting anchor cable with a “hollow-solid-hollow” cable body structure in the embodiment.
[0026] Figure 4Schematic diagram of the structure of the second hard push tube in (a) three-dimensional and (b) cross-section.
[0027] In the figure: 1. Hollow cable body, 2. Anchor, 3. First hard push pipe, 4. Grouting outlet, 5. Locking hoop, 6. Solid cable body, 7. Grouting plug, 8. Second hard push pipe, 81. Strip open groove, 100. Coal mining working face, 200. Newly excavated tunnel, 300. Tunnel on one side of the coal mining working face, 400. Advance grouting range, 500. Delay grouting range, 600. Grouting anchor cable, 700. Channel steel beam.
[0028] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION
[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Terms such as "upper," "lower," "left," "right," "center," and "one" used in the preferred embodiments are for ease of description and are not intended to limit the scope of the present invention. Changes or adjustments to these relative terms, without substantially altering the technical content, are also considered within the scope of the present invention.
[0030] The present invention provides a method for reinforcing a narrow coal pillar in a roadway facing mining by using a tension grouting anchor beam. In the roadway facing mining, a newly excavated roadway 200 and an adjacent coal mining face 100 advance in opposite directions. A narrow coal pillar is used to protect the roadway between the newly excavated roadway 200 and the roadway 300 on one side of the coal mining face. As the coal mining face 100 gradually advances, the reinforcement of the narrow coal pillar in the roadway facing mining is carried out in stages according to the distance between the excavation head of the newly excavated roadway 200 and the coal mining face 100. According to the advance and lag effects of the coal mining face, the part outside the advance mining influence range of the coal mining face, the part within the advance mining influence range of the coal mining face, and the lag mining influence range of the coal mining face are determined. The specific division diagram is shown in the figure. Figure 1 As shown, the white arrow in the figure indicates the mining direction of the coal mining face.
[0031] The specific steps for the reinforcement method of narrow coal pillars facing mining roadways are as follows:
[0032] S1, determine the installation spacing and length of the tension grouting anchor beam
[0033] The spacing of the grouting anchor beams is determined based on the actual engineering conditions, including the geological conditions of the underground working face and the newly excavated roadway, the reserved coal pillar width, the original roadway support parameters, and the progress of the coal mining face 100. It is generally twice the anchor support spacing in the original support. In this embodiment, a 9m wide protective coal pillar is left between the newly excavated roadway 200 and the coal mining face 100. The grouting anchor cables are designed to be 9.6m long, with a spacing of 1600mm x 1600mm.
[0034] S2, new tunnel excavation
[0035] The new tunnel is excavated normally, and the original support (anchor rods, anchor cables, anchor nets, etc.) is constructed normally according to the original support regulations of the coal mine until the head of the new tunnel 200 is about 350 meters away from the coal mining working face 100. According to the "Coal Mine Safety Regulations", excavation should be stopped (at this time, the distance between the head of the new tunnel and the coal mining working face is much larger than the advance impact range of the working face).
[0036] S3, construction of tension grouting anchor beam
[0037] For the narrow coal pillar outside the range of the advanced mining in the coal mining face, in addition to the original support of the tunnel, the tension grouting anchor beam is constructed. Thereafter, as the coal mining face 100 advances, the reinforcement range of the tension grouting anchor beam is also extended forward synchronously.
[0038] The tension grouting anchor beam is composed of two grouting anchor cables 600 and a channel steel beam 700 that penetrate the narrow coal pillars in the roadway. The grouting anchor cable 600 includes a solid cable body 6 that constitutes a "hollow-solid-hollow" cable body structure and two hollow cable bodies 1 connected to the two ends of the solid cable body 6. A first hard push tube 3 is sleeved on the solid cable body 6, and a second hard push tube 8 is sleeved on the hollow cable body 1. An extrudable and expandable locking hoop 5 is provided between the first hard push tube 3 and the second hard push tube 8. A grouting outlet 4 is provided on the hollow cable body 1, and a strip-shaped open groove 81 is provided on the wall of the hard push tube. The grouting outlet 4 is located in the strip-shaped open groove 81, and the strip-shaped open groove 81 is used as a avoidance opening for the grouting outlet 4; a grouting plug 7 and an anchor 2 are sleeved at both ends of the hollow cable body 1. The grouting plug 7 is located at the end of the hollow cable body 1 away from the solid cable body 6, and the anchor 2 is located on the outside of the grouting plug 7 for fixing to the channel steel beam 700.
[0039] The total length of the grouting anchor cable 600 is 9.6m, and the solid cable body 6 accounts for about 1 / 3 of the total length. Anchor cable holes are drilled horizontally at 700mm and 2300mm from the bottom plate on the narrow coal pillar to pass the grouting anchor cable 600 through the narrow coal pillar. 14#-L2000mm / 2 type channel steel beams 700 are used to support both sides of the grouting anchor cable 600. The spacing between the anchor cables is 1600mm×1600mm. During the installation process, the second hard push pipe 8 applies a thrust toward the first hard push pipe 3 to expand the soft rubber locking hoop 5 and seal the anchor cable hole. The arrangement of the tension grouting anchor cable beam is shown in the figure. Figure 2 As shown, the structure of the grouting anchor cable 600 is as follows: Figure 3 As shown, the structure of the second hard push tube 8 is as follows Figure 4 shown.
[0040] S4, advanced grouting
[0041] As the coal face gradually advances, the constructed tension-grouting anchor beams gradually enter the area affected by the advanced mining. At this point, the narrow coal pillar on the mining face side is first affected, causing cracks to develop. Testing using borehole imaging or geological radar reveals that when the cracks within the narrow coal pillar reinforced by the tension-grouting anchor beams exceed the anchoring range of the original support bolts or one-third of the coal pillar width, the time for advanced grouting is determined. In the roadway 300 on the coal face side, grouting is performed on all anchor cables within the 400-degree advanced grouting range that meets the grouting requirements. Because the grouting anchor cables used have a "hollow-solid-hollow" cable structure and expandable locking hoops, when the appropriate grouting pressure is applied, the grouting operation will only reinforce the area on the coal face side, preventing slurry from seeping into the newly excavated roadway. This reinforces the narrow coal pillar through grouting and repairs damaged anchors.
[0042] S5, delayed grouting
[0043] As the mining face continues to advance, the constructed tension grouting anchor beams gradually enter the area affected by delayed mining behind the mining face. During this process, cracks develop again within the narrow coal pillars. Testing using borehole imaging or geological radar indicates that the crack development within the narrow coal pillars within the area reinforced by the tension grouting anchor beams exceeds the anchoring range of the original support bolts or one-third of the coal pillar width, indicating the time for delayed grouting. On one side of the newly excavated roadway, grouting is performed on all anchor cables within the delayed grouting range of 500 mm that meet the grouting requirements. The grouting pressure for delayed grouting can be greater than that for advanced grouting to ensure that the slurry penetrates the entire narrow coal pillar. Narrow coal pillars damaged again by mining after the initial grouting are reinforced with secondary grouting to repair damaged anchors.
[0044] S6, grouting parameter optimization
[0045] After completing the advance and delayed grouting operations, the deformation of the coal pillar is continuously monitored, and the grouting parameters of the advance and delayed grouting are adjusted in a timely manner according to the actual situation.
[0046] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.
Claims
1. A method for reinforcing a narrow coal pillar in a mining roadway by using a tension grouting anchor beam, characterized in that: The tension grouting anchor beam for reinforcing the narrow coal pillar in the mining lane is composed of a grouting anchor and a channel steel beam for anchoring at both ends of the grouting anchor. The grouting anchor includes a solid cable body and two hollow cable bodies connected to the two ends of the solid cable body. A first hard push tube is sleeved on the solid cable body, and a second hard push tube is sleeved on the hollow cable body. An extrudable and expandable locking hoop is provided between the first hard push tube and the second hard push tube. A grouting outlet is provided on the hollow cable body, and a strip-shaped opening groove is provided on the tube wall of the hard push tube. The grouting outlet is located in the strip-shaped opening groove. In the mining roadway, the new roadway and the adjacent coal mining face are advanced towards each other. A narrow coal pillar is used to protect the roadway between the new roadway and the roadway on the side of the coal mining face. As the coal mining face gradually advances, the reinforcement of the narrow coal pillar of the mining roadway with tension grouting anchor beams is divided into three stages: In the first stage, the construction of tension grouting anchor beams: For the portion of the narrow coal pillar outside the range of influence of the advanced mining of the coal mining face, an anchor cable drill hole is opened on the narrow coal pillar in this portion, which runs from the newly excavated roadway to the roadway on the side of the coal mining face, and the grouting anchor cable is installed in the anchor cable drill hole. The two ends of the grouting anchor cable are anchored by a channel steel beam. When installing the grouting anchor cable, the first hard push tube and the solid cable body are located in the middle of the anchor cable drill hole. The second hard push tube applies a thrust toward the first hard push tube to expand the locking hoop and seal the anchor cable drill hole. The second stage is advance grouting reinforcement: Monitor the crack development range of the narrow coal pillar within the advance mining influence range of the coal mining face, and determine the timing of advance grouting based on the crack development range of the narrow coal pillar reflected by the test results. Then, advance grouting is carried out on the narrow coal pillar through grouting anchor cables in the roadway on one side of the coal mining face. The third stage, delayed grouting reinforcement: For the narrow coal pillar within the range of delayed mining influence of the coal mining face, the crack development range of this narrow coal pillar is monitored, and the timing of advance grouting is determined based on the crack development range of the narrow coal pillar reflected by the test results. The narrow coal pillar is then delayed grouted by grouting anchors in the newly excavated tunnel.
2. The method for reinforcing a narrow coal pillar in a mining roadway by using a tension grouting anchor beam according to claim 1 is characterized in that: The grouting anchor cable also includes a grouting plug and an anchor mounted on the hollow cable body. The grouting plug is located on one end of the hollow cable body away from the solid cable body, and the anchor is located outside the grouting plug for fixing to the channel steel beam.
3. The method for reinforcing narrow coal pillars in mining lanes by using tension grouting anchor beams according to claim 1 is characterized in that: A plurality of grouting outlets are provided along the axial direction of the hollow cable body and at intervals.
4. The method for reinforcing a narrow coal pillar in a mining roadway by using a tension grouting anchor beam according to claim 1 is characterized in that: The locking hoop is made of rubber.
5. The method for reinforcing narrow coal pillars in mining lanes by using tension grouting anchor beams according to claim 1 is characterized in that: The solid cable body is 1 / 3 of the length of the anchor cable drilling hole, and the lengths of the two hollow cable bodies located in the anchor cable drilling hole each account for 1 / 3 of the length of the anchor cable drilling hole.
6. The method for reinforcing a narrow coal pillar in a mining roadway by using a tension grouting anchor beam according to claim 1, characterized in that: The scope of fracture development in narrow coal pillars is monitored by borehole imaging or geological radar.
7. The method for reinforcing narrow coal pillars in mining lanes by using tension grouting anchor beams according to claim 1, characterized in that: In the second and third stages, when the development range of the cracks in the narrow coal pillar exceeds the anchoring range of the original support of the narrow coal pillar or 1 / 3 of the width of the narrow coal pillar, the corresponding advance grouting and delayed grouting are started.
8. The method for reinforcing a narrow coal pillar in a mining roadway by using a tension grouting anchor beam according to claim 1, characterized in that: The grouting pressure of the delayed grouting should be greater than the grouting pressure of the advanced grouting.
9. The method for reinforcing a narrow coal pillar in a mining roadway by using a tension grouting anchor beam according to any one of claims 1 to 8, characterized in that: The tension grouting anchor cable beam is composed of two grouting anchor cables arranged at intervals and channel steel beams for anchoring at both ends of the grouting anchor cables. The same side of the two grouting anchor cables arranged at intervals is anchored on the same channel steel beam.